In the field of microstructural analysis of surfaces, surfaces of metal, minerals, or any other desired surface are cut as a thin wafer, mounted in a plastic block, polished, and microscopically analyzed. The step of mounting the wafer-like sample in plastic permits the easy handling of a very thin wafer of material, and has been performed in the prior art, for example, by the Simplimet II brand of specimen molding press, sold by Buehler Ltd. of Lake Bluff, Illinois. This prior art specimen press carries a cylindrical molding chamber having a ramhead sealingly movable along the length of the chamber to pressurize a mass of plastic which overlies the wafer-like sample to be mounted in the plastic. The prior art unit uses manually pumped pneumatic pressure to drive the piston, while the plastic is heated to melting to form an integral plastic block, with the sample carried on one face of the plastic block.
Such a manual system requires hand pumping to a pressure that is greater than the desired molding pressure, to account for the fact that the plastic molding compound will decrease in volume as the molding proceeds, thus causing a reduction in the pressure. Thus, such a prior art system, while effective in many circumstances, is not as precise in its pressure application as may often be desired, without careful and continuous monitoring.
Also, in prior art specimen mounting presses, it has been necessary to be sure that there is precise, coaxial alignment between the tubular molding chamber and the axis of motion of the ram, in order to avoid scouring and possible damage to the molding chamber or ram. In accordance with this invention, improvements are provided in which automated, precise specimen mounting may be provided, with precise control not only of pressure under the dynamic conditions of molding, but also precise control of molding time and temperature. Similarly, the length of the molding cycle may be shortened according to this invention, while the molding apparatus is adapted to be less subject to damage or binding through misalignment of the tubular molding chamber with the axis of motion of the ram.